Mana users seem not to be compensated for their gating
In a previous discussion, I made the assertion that mana-using champions tend either to suffer from being mana-gated, spend money on mana purchases that manaless champions don't need, or both: and that they aren't compensated for this. A questioner asked me whether or not any of the following existed, implying that they're the unique strengths of mana-using champions: I disagree.
Manaless champions with CC:

Manaless champions with AoE:

Manaless champions that are threatening after they've blown their CDs:

Manaless champions with game-changing ultimates:

Manaless champions who are threatening early, mid and late:

I contend that, other than the ability to be relegated to support if they wash out of another position, I don't know what mana champions have to compensate them for their gating as compared to the champions above. You're welcome to point-by-point disagree with my examples, but then I'll just highlight other weaknesses of champions that use mana... I believe it's impossible to draw a line that says "mana-using champions can do X better than anyone else" because no such line exists.
You know the drill. Upvote if you agree that mana-users need defined strengths (or manaless champs need defined weaknesses), comment if you disagree and we'll see if I can't change your mind.
other than to 3 v 1 him".
is a nice example of a champ people get butthurt over, but I can really start listing them if we need to.
Use mana.

People would probably just have a second Duo lane rather then try jungleing against her
Midlane would be impossible for anyone else to really even play in much less dominate